Mask film to form relief images and method of use

Abstract

A mask-forming film has a transparent layer between the imageable layer and the carrier sheet, which transparent layer has a refractive index that is lower (by at least 0.04) than that of the carrier sheet or any immediately adjacent layer between it and the carrier sheet. This lower refractive index layer modifies the path of incident radiation during mask image transfer so as to provide steeper shoulder angles in the relief image solid areas.

1. A film comprising a carrier sheet having thereon, in order:
 a) a transparent layer comprising a fluoroelastomer and having a thickness of from about 0.25 to about 10 μm, said transparent layer optionally including an adhesion promoter, and the transparent layer having a refractive index of at least 0.04 lower than the refractive index of the carrier sheet, 
 b) an intermediate layer comprising a poly(vinyl alcohol), cellulosic polymer, poly(vinyl butyral), or hydrolyzed styrene maleic anhydride, or a thermally resistant polymer, and having a thickness of from about 0.1 to about 10 μm, said intermediate layer optionally including a crosslinking agent, coating aid, surfactant, or release-enhancing agent, 
 c) a barrier layer comprising a poly(cyanoacrylate) or nitrocellulose, and an infrared radiation absorbing dye, and optionally metal oxide particles or crosslinking agents, 
 d) an imageable layer comprising an infrared radiation absorbing dye and a UV-absorbing colorant dispersed in a polyurethane, poly(vinyl butyral), acrylamide polymer, nitrocellulose, or polyacetal binder, and 
 e) an overcoat comprising a methacrylic acid copolymer and fluoropolymer particles. 
 
     
     
       2. The film of  claim 1  wherein the transparent layer has a refractive index at least 0.08 lower than the refractive index of the carrier sheet. 
     
     
       3. The film of  claim 1  wherein the barrier layer includes an infrared radiation absorbing compound. 
     
     
       4. The film of  claim 1  wherein the infrared radiation absorbing compound in the imageable layer is an IR dye. 
     
     
       5. The film of  claim 1  wherein the carrier sheet is a polyester, fluorine polyester polymer, polyethylene polypropylene, polybutadiene, polycarbonate, polyacrylate, polyvinyl chloride or copolymer thereof, or hydrolyzed or non-hydrolyzed cellulose acetate, and is from about 20 to about 200 μm thick, and optionally includes an adhesion promoter. 
     
     
       6. The film of  claim 1  wherein the transparent layer has a thickness of from about 0.4 to about 10 μm. 
     
     
       7. The film of  claim 1  wherein the intermediate layer further comprises an adhesion promoter.